Conventional technology in which a striker is projected from a vehicle body, at aback opening thereof, and a lock device which is engaged with and disengaged from the above-mentioned striker is installed to a rear door for opening and closing the back opening is disclosed in, e.g., Patent Literature 1.
This lock device includes a hook (latch) which is rotatable between an unlocked position to be disengaged from a striker and a locked position to be engaged with the striker and which is biased to rotate toward the unlocked position; a pawl (ratchet) rotatable between an engaging position to be engaged with the hook positioned in the locked position and a non-engaging position to be disengaged from the hook; a motor which rotates a worm by electric power; a worm wheel (cam member) which is in mesh with the worm and has a cam surface provided around the rotation axis thereof; and a lock release lever (output lever) which has a cam follower which comes in contact with the cam surface of the worm wheel in a direction substantially orthogonal to the rotation axis of the worm wheel, and has a press portion (output portion) which presses the pawl, wherein a portion of the lock release lever (the portion on which the cam follower is formed and a peripheral part thereof) faces the worm with a slight gap created between the lock release lever and the worm in a direction parallel to the above-mentioned rotation axis.
When the rear door is in the fully-closed position so as to close the above-mentioned back opening, the hook is in the locked position while engaged with the striker, and the pawl is in the engaging position to hold the hook in the locked position, so that the rear door is held in the fully-closed position by the lock device and the striker.
In this state, for instance, upon a lock release switch provided inside the vehicle being pressed, the motor is supplied with power and rotates. Thereupon, the worm wheel which receives a rotational force from the worm rotates, and the lock release lever which receives a force from the cam surface via the cam follower rotates, so that the press portion of the lock release lever engages with the pawl and rotates the pawl to the non-engaging position. Thereupon, the hook that is biased to rotate by a biasing device rotates to the unlocked position to release the striker, which brings the rear door into a state that is capable of opening the above-mentioned back opening.